1. Field of the Invention
The present invention relates generally to the field of medical instruments for retrieving foreign articles from patients. More particularly, it concerns an apparatus for use as a snare or foreign body retrieval device that is guidewire-compatible and includes a continuously-adjustable, laterally-oriented loop.
2. Description of Related Art
During medical procedures which utilize catheters, guidewires, pacemaker leads, or other medical devices, a portion of the device can sometimes break off and be left within the patient. The detached portion may then travel within the patient""s vascular system and come to rest in a luminal organ, vein or artery, and usually at a branching point or in the heart. Leaving these foreign bodies within the patient can be quite harmful, and may result in complications like sepsis, perforation, thrombosis, arrhythmias, myocardial necrosis, or even death. Therefore, it is necessary and urgent to remove the foreign body from the patient.
Similarly, several interventional radiological procedures involve implantation of different devices within the body. Recently, embolization coils, stents and vena cava filters, among others, have been frequently used. Misplacement and/or dislodgment of these devices may result in serious consequences and necessitate their removal (Galal et al., Eur. Heart J., 1997; Ing and Bierman, Cardiovasc. Intervent. Radiol., 1995; Siegel and Robertson, JVIR, 1993; Lipton, JVIR, 1995).
The percutaneous removal of foreign bodies or devices has become acceptable because it is relatively easy and safe. However, current devices possess certain shortcomings that inhibit their ease and range of use.
The Amplatz xe2x80x9cGoose Neckxe2x80x9d snare, commercially available from Microvena Corporation of White Bear Lake, MN, is currently the most popular snare. Described in U.S. Pat. No. 5,171,233 to Amplatz et al. (1992), the Amplatz snare consists of a superelastic wire that is bent in half. The two wire segments created as a result of the bend are bonded together to eliminate the possibility of moving the segments relative to each other. A loop is fashioned at the location of the bend. The loop is bent at its proximal end (i.e., the end of the loop closest to the operator) such that the loop is oriented at an angle to the bonded wire segments. Because the wire segments are bonded together to prevent the relative movement of either, the size of the loop is fixed.
In order to operate the Amplatz snare, the loop is constrained (pinched) and inserted into a catheter. Once positioned in the patient, to utilize the loop, the position of the catheter is maintained, and the folded wire is pushed until the loop is fully extended beyond the tip of the catheter. It then returns to its unconstrained configuration. Prior to being completely extended beyond the tip of the catheter, the loop will remained constrained and useless.
After the loop is formed, the Amplatz snare may be manipulated until the loop passes over the foreign body to be retrieved. Then, by maintaining the position of the folded wire, the catheter may be advanced over the bonded segments and the loop until the foreign body is firmly wedged between the distal end of the loop and the catheter. This process may also be achieved by holding the catheter steady and withdrawing the bonded wire segments, or both may be manipulated at once. The snare may then be removed from the patient along with the laterally-oriented foreign body.
A purported advantage of the bonded wire segments and fixed loop of the Amplatz snare is that the operator need only utilize one hand to form the loop, in contrast to other snares in which the relative movement of the two wire halves may be required in order to form a useful loop. (See, e.g., the snare disclosed in Bett et al., Med. J Aust., 1971)
The fixed nature of the loop of the Amplatz snare, however, poses certain shortcomings. For example, because the loop is fixed, having only one or two snare sizes may not be feasible to efficiently remove foreign bodies of all sizes in the least disruptive manner to the patient. Obviously, while having a snare with a relatively large loop may be useful for retrieving correspondingly large foreign bodies in sufficiently sized vessels or structures, a patient could be traumatized by retrieving a more diminutively-sized foreign body with the same snare. Specifically, it would not be beneficial to the patient to retrieve a small foreign body lodged in a small vessel or structure with an Amplatz snare having a loop that is larger than the size of the vessel. The vessel or structure could be traumatized by the pressure the loop would exert on the wall thereof during the procedure. As a result, it is not possible to feasibly utilize one or two Amplatz snares for the retrieval of foreign bodies of virtually all sizes.
Further, as a result of the fixed nature of the loop and the fact that it must be extended beyond the tip of the catheter before it is formed and operational, if a foreign body were positioned in a way that made it more feasible to surround it by withdrawing the loop toward the operator rather than by advancing the loop away from him or her, the tip of the catheter would need to be positioned distally of the distal end of the foreign body prior to forming the loop. As a result, the vessel or structure would need to possess a sufficient amount of space distal of the foreign body in which the constrained loop could be extended during its formation. If such space did not exist, such as at a branch or bifurcation, the Amplatz snare would be useless in that application.
Another shortcoming of the Amplatz snare is that prior to removing it, the foreign body must be pinched or wedged between the distal end of the loop and the distal tip of the catheter. As a result, in cases in which the foreign body is straight or slightly bent, the foreign body will be oriented transversely to the catheter as it is being withdrawn. Consequently, the wall of the vessel or structure from which it is removed may be traumatized by the laterally-oriented foreign body scraping against it as the foreign body is extracted. For the same reason, negotiating tortuous passageways may be difficult, and the foreign body may become caught or wedged in a passageway and require surgical removal.
Yet another shortcoming of the Amplatz snare is that it is not guidewire compatible. The use of a guidewire is neither disclosed nor suggested by the Amplatz patent. Thus, the catheter in which the folded wire is housed must be used to guide the snare to its desired location. Further, the use of a guidewire with the Amplatz snare would only add to its bulk since a larger delivery catheter would be needed in order to accommodate the two twisted wire segments bonded together and the guidewire.
The surgical snare disclosed in U.S. Pat. No. 5,342,371 to Welter et al. (1994) (commercially available from Cook Inc., Bloomington, Ind.) (the xe2x80x9cWelter snarexe2x80x9d) suffers from some of the same shortcomings as the Amplatz snare, but addresses one of them. The Welter consists of an elongated member in which two longitudinally spaced-apart ports are provided. A stainless steel wire is threaded out of one of the ports, helically wrapped around the elongated member, and threaded back into the member through the other port, thereby forming a collapsed, stainless steel helical snare loop external of the member. The distal end of the stainless steel wire is attached to the distal end of the member. The stainless steel helical snare loop may be opened and closed by manipulating a sliding handle affixed to the proximal end of the member. By attaching the distal end of the stainless steel wire to the distal end of the elongated member, the Welter snare addresses the problem recognized in the Amplatz patent of having to move one end of the stainless steel wire forming the helical snare loop relative to the other by fixing the position of the distal end of the wire, instead of by bending the wire and bonding the two wire segments. As a result, the stainless steel helical snare loop of the Welter snare may not only be operated with one hand, a goal achieved by the bonded wire segments of the Amplatz snare, but may also be continuously adjusted.
The member is closed at its distal end and, as a result, the Welter snare is not guidewire compatible. As such, it suffers from the same shortcomings in this regard as does the Amplatz snare. Further, the use of a guidewire is not suggested in the Welter patent because the function of a guidewirexe2x80x94namely controlxe2x80x94is taught as being accomplished by a stainless steel wire braid embedded as a torque control member in the wall of the member. This embedded stainless steel wire braid purportedly facilitates directional control of the member through the vascular system of the patient. The wire braid is embedded in the wall of the member during the extrusion of the member.
The Welter patent discloses that the ports in the elongated member are spaced longitudinally apart from each other. The stainless steel wire threaded through the ports, which forms the helical snare loop, is wrapped around the elongated member such that the stainless steel loop may be formed and operated without it being laterally deformed or kinked. In this regard, the Welter patent recognizes the shortcomings of loops that may kink during use, and appears to address this problem by ensuring the formation of a helical snare loop (i.e., one that is not laterally deformed) through the longitudinal spacing of the ports in the member and the orientation of the stainless steel wire between the ports.
A shortcoming of this design, however, is the fact that the stainless steel wire occupies space around the circumference of the member during its introduction into and movement throughout the body of the patient. As a result, the stainless steel wire could disrupt fluid flow, or even cause damage to the vessel or luminal organ in which it is placed if, for example, the vessel or luminal organ is irregular in shape due to the presence of plaque, etc. Additionally, as the stainless steel helical snare loop is opened, utilized, and closed, it occupies space within the patient along the entire length of the member located between the two ports. Consequently, the vessel or luminal structure in which the Welter snare is utilized is subject to the potential damage just described along its length that corresponds to the length of the member between the two ports. Similarly, as the stainless steel helical snare loop is operated, the potential for the disruption of fluid flow increases because the size of the amount of stainless steel wire present in the vessel or luminal organ increases.
Another snare is disclosed in an article from The Medical Journal of Australia (xe2x80x9cthe Australian snarexe2x80x9d) and includes a catheter having two small holes in it, and a nylon fishing line threaded through the holes (Bett et al, Med. J. Aust., 1971). The ends of the nylon line extend beyond the proximal hub of the catheter, the hub being formed from a short collar of polyurethane tubing. The location of the holes is not clear from the article. The Australian snare is also reviewed in another article that depicts the holes in the snare as being longitudinally spaced-apart in FIG. 4 thereof (Bloomfield, Cathet. Cardiovasc. Diagn., 1978).
Whatever the position of the holes in the Australian snare, it suffers from one shortcoming recognized in the Amplatz patentxe2x80x94the need for the relative movement of the ends of the nylon line to form a useful loop. Although an operator could hold the two ends of the nylon line together and advance both at the same type in attempting to form the loop, the rigidity of the nylon line could pose certain problems. For example, it is likely that the nylon line, having no more rigidity than that of fishing line, would be difficult to smoothly advance through the holes in the catheter. (The limpness of the line is depicted in FIG. 4 of the Bloomfield article.) That is, the relatively limp nylon line would likely have a tendency to buckle as the loop is formed. This would likely be especially true if both ends of the line were held together and advanced simultaneously. Another problem posed by the relative limpness of the nylon line is that if the position of the loop formed was disrupted by either the foreign body or a portion of the patient""s anatomy, the lack of rigidity of the nylon line could prevent the operator from readily re-achieving an operable configuration of the misshapen loop.
The problems pointed out with the foregoing snares are not intended to be exhaustive but rather are among many that tend to impair the effectiveness of previously known snares. Other noteworthy problems may also exist; however, those presented above should be sufficient to demonstrate that previous techniques appearing in the art have not been altogether satisfactory, particularly in providing a simply-constructed snare that is easily-maneuverable and capable of grasping articles in a reliable and minimally-invasive fashion.
In one respect, the invention is a retrieval device that includes, but is not limited to, a first catheter that has a distal end, a proximal end, a lumen system configured to accept at least one wire such that the at least one wire may extend beyond either end of the first catheter, and an opening system through which a loop may be formed; and a wire that has a distal end attached to the first catheter, and a proximal end. The proximal end of the wire may be manipulated to cause a portion of the wire to form a loop external of the first catheter. The loop is capable of grasping foreign bodies within a patient.
The retrieval device may also include, but is not limited to, a guidewire that is configured to be placed within the lumen system. The opening system may include first and second openings. The first opening may be spaced from the distal end of the first catheter by a first distance, the second opening may be spaced from the distal end of the first catheter by a second distance, and the first and second distances may be substantially equal. The loop that may be formed may have an open position that is substantially circular in shape. The lumen system may be a single lumen that may be tapered. The lumen system may include a first lumen and a second lumen, and the wire may be configured to be placed within the first lumen and extend beyond either end of the first catheter. The first catheter may be include at least two segments connected together. The retrieval device may also include, but is not limited to, a handle connected to the wire. The handle may be manipulated to cause the portion of the wire to pass through the opening system and form the loop capable of grasping foreign bodies within the patient. The retrieval device may also include, but is not limited to, a reinforcing loop material connected to the wire such that when the proximal end of the wire is manipulated to form the loop, at least a portion of the loop is adjacent to the reinforcing loop material. The reinforcing loop material may be made from TEFLON, NYLON or PTFE. The reinforcing loop material may be made from stainless steel. The reinforcing loop material may be made from nitinol. The reinforcing loop material may be made from tungsten or platinum. The retrieval device may also include, but is not limited to, a reinforcing pusher material connected to the wire proximate the proximal end of the wire. The reinforcing pusher material may be made from nitinol or stainless steel, for example. The reinforcing pusher material may be a second catheter, and the second catheter may be manipulated to cause the portion of the wire to pass through the opening system and form the loop capable of grasping foreign bodies within the patient. The retrieval device may also include, but is not limited to, a first hemostasis valve connected to the distal end of the first catheter, and a second hemostasis valve connected to the distal end of the second catheter. The retrieval may also include, but is not limited to, a side-arm adapter connected to the distal end of the first catheter. The retrieval device may also include, but is not limited to, a locking device connected to the side-arm adapter. The retrieval device may also include, but is not limited to, a hemostasis valve connected to the locking device.
In another respect, the invention is a retrieval device that includes, but is not limited to, a first catheter that has a distal end, a proximal end, a lumen system configured to accept at least one wire such that the one wire may extend beyond either end of the first catheter, and an opening system through which a loop may be formed; a first wire configured to be placed within the lumen system and extend beyond either end of the first catheter; and a second wire that has a distal end and a proximal end. The distal end of the second wire is attached to the first catheter. The proximal end of the second wire may be manipulated to cause a portion of the second wire to pass through the opening system and form a loop capable of grasping foreign bodies within a patient.
The opening system may include two openings oriented substantially equidistant from the distal end of the first catheter. The loop that may be formed may have an open position that is substantially circular in shape. The lumen system may be a single lumen. The lumen system may include a first lumen and a second lumen, the first wire may be configured to be placed within the first lumen and extend beyond either end of the first catheter, and the second wire may be placed within the second lumen. The first catheter may be tapered. The first catheter may include at least two segments connected together. The second wire may be tapered. The retrieval device may also include, but is not limited to, a handle connected to the second wire, and the handle may be manipulated to cause the portion of the second wire to pass through the opening system and form the loop capable of grasping foreign bodies within the patient. The retrieval device may also include, but is not limited to, a reinforcing loop material connected to the second wire such that when the proximal end of the second wire is manipulated to form the loop, at least a portion of the loop is adjacent to the reinforcing loop material. The retrieval device may also include, but is not limited to, a reinforcing pusher material connected to the second wire proximate the proximal end of the second wire. The reinforcing pusher material may be a second catheter configured to accept the first wire, and the second catheter may be manipulated to cause the portion of the second wire to pass through the opening system and form the loop capable of grasping foreign bodies within the patient. The retrieval device may also include, but is not limited to, a first hemostasis valve connected to the distal end of the first catheter, and a second hemostasis valve connected to the distal end of the second catheter. The retrieval device may also include, but is not limited to, a side-arm adapter connected to the distal end of the first catheter. The retrieval device may also include, but is not limited to, a locking device connected to the side-arm adapter. The retrieval device may also include, but is not limited to, a hemostasis valve connected to the locking device.
In another respect, the invention is a method for retrieving a foreign body from a patient that includes, but is not limited to, inserting a guidewire into the patient; maneuvering the guidewire to an appropriate location within the patient; advancing a first catheter, which has a distal end, a proximal end, an opening system through which a loop may be formed, and a wire attached thereto that is capable of forming a loop, over the guidewire; manipulating the wire to capture the foreign body with the loop; and withdrawing the first catheter and foreign body to retrieve the foreign body from the patient.
The opening system may include first and second openings. The first opening may be spaced from the distal end of the first catheter by a first distance. The second opening may be spaced from the distal end of the first catheter by a second distance. The first and second distances may be substantially equal. The loop that may be formed may have an open position that is substantially circular in shape. The first catheter may include at least two segments connected together. The method may also include, but is not limited to, a reinforcing loop material connected to the wire such that when the wire is manipulated to form the loop, at least a portion of the loop is adjacent to the reinforcing loop material.